<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
  <style media="screen">

  .s456{
      background-color: green;
  }
  .l456{
    background-color: red;
  }
  </style>
  </head>
  <body>
    <p class="l456">sdf</p>
    <p class="s456">1545</p>

    <script type="text/javascript">
    let a = "name";
      let obj = {name:"le", age:15}
      console.log(obj);
      // delete obj.name;
      // console.log(obj);

      console.log(obj.age);
      console.log(obj[a]);
      console.log(obj.length);
    </script>
  </body>
</html>
